A Patent Changes Hands on Paper, Not on Agreement

Patents are property. They can be sold, gifted, inherited, pledged as collateral, and swept into an acquisition. But unlike most property, nothing about the transfer is implied by conduct, and there is no equivalent of handing over the keys. A patent moves only when a signed written instrument says it moves. If that instrument is missing, vague, or unrecorded, the ownership question resurfaces at the worst possible moment: during due diligence, during a licensing negotiation, or when standing to sue is challenged.

The mechanics are simple. What makes assignments go wrong is treating them as an afterthought to the deal rather than the deal itself.

The Situations Where Ownership Moves

The obvious case is an outright sale. The more common cases are quieter.

  • Inventor to company. A patent is always granted to human inventors first. Getting it into the company that will commercialize it requires an explicit assignment, and the employment rules that govern whether the company is entitled to demand one are in who owns an invention made at work.
  • Contractor to client. Absent a written assignment, a contract engineer or design firm can own what they invented for you even though you paid for it. The default rules surprise most founders and are laid out in who owns the IP a contractor creates.
  • Founder to startup. Almost every seed investor requires that all founder IP has been assigned to the entity before wiring money.
  • Acquisition. Patents transfer either by naming them individually in an asset purchase or by operation of law in a merger. Asset deals go wrong when a schedule omits an application.

What the Assignment Document Must Contain

A patent assignment is short, often a single page, and the requirements are few but strict. It must be in writing and signed by the assignor. An oral promise transfers nothing.

It must identify the property unambiguously. Use the patent number for granted patents and the application serial number plus filing date for pending applications, and state explicitly whether the transfer sweeps in continuations, divisionals, continuations-in-part, reissues, foreign counterparts, and the right to sue for past infringement. That last item gets omitted constantly, and without it the buyer cannot pursue infringement that occurred before the transfer date.

It should recite consideration, name the assignee exactly as the legal entity is registered, be dated, and include a further-assurances clause obligating the assignor to sign whatever additional documents foreign patent offices demand later. Many jurisdictions require notarization or legalization for their own registries even where the US does not, so a notarized signature is cheap insurance if any foreign family members exist.

Recording at the USPTO, and the Three-Month Trap

The assignment is legally effective between the two parties when signed. Recording it with the USPTO does something different: it puts the world on notice.

US law protects a later good-faith purchaser who pays value without knowing about an earlier transfer. If the first assignee does not record, and the original owner then assigns the same patent again to someone who has no notice, the second buyer can win. The protection for the first assignee is to record within three months of the assignment date, or at least before the subsequent transfer. Miss both and you can own nothing despite holding a signed deed.

Recording is electronic, takes a cover sheet identifying the parties and properties, costs very little, and turns around in days. The resulting chain of title is public, which is precisely what makes it useful to the next buyer, investor, or licensee.

Diligence Before You Sign Anything

Buying a patent means buying whatever is wrong with it. Work through this before money moves.

  • Chain of title. Pull the recorded assignment history and trace it from the named inventors to the current seller with no gaps. A gap of one signature makes the whole chain unenforceable.
  • Inventorship. Incorrect inventorship is a defect that can invalidate a patent. If someone who contributed to the claims was left off, or someone who did not contribute was added, fix it before the transfer, not after.
  • Co-owners. In the US, each co-owner can independently license the patent without accounting to the others, which means a seller holding half may be selling you a right that a rival already has. The dynamics are in two inventors, one patent.
  • Existing licenses and liens. An exclusive license granted earlier survives the sale and can leave you owning a patent you cannot practice. Security interests from a lender do the same.
  • Legal status and fees. Confirm the patent is alive and that the next payment window is known, using the checks in how to check if a patent is still in force and the schedule in patent maintenance fees. A lapsed patent is worth nothing and revival is not guaranteed.
  • Prosecution history. Read the file wrapper. Claim scope narrowed during prosecution is claim scope you are not buying, regardless of what the abstract implies.

Assignment or License

Assignment moves ownership permanently. The assignor keeps nothing, not even the right to practice the invention, unless a grant-back is written in. Licensing keeps ownership with the original holder and grants defined rights, which can be exclusive or not, limited by field of use, territory, or term, and revocable on breach. The structural differences and the money mechanics are covered in patent licensing.

An exclusive license in a single field can look almost identical to an assignment in practice while leaving the owner free to license elsewhere and to keep collecting after the licensee loses interest. Sellers who take a lump sum for a patent that later underpins a large product line usually regret it, which is why running the valuation exercise in how to value a patent before choosing a structure is worth the effort.

Common Failures Worth Avoiding

The recurring ones: assigning a granted patent while forgetting the pending continuation that carries the broader claims; naming a company that was never actually incorporated under that exact name; omitting the right to sue for past damages; forgetting foreign counterparts, which need separate recordation in each national office and often on their own forms; and signing before confirming that every inventor has assigned upstream. Each of these takes minutes to prevent and months to unwind.

Sort the Ownership Before It Costs You a Deal

Ownership defects almost always surface during a funding round or an acquisition, when there is no time to chase signatures from a contractor you last spoke to two years ago. Projects House helps clients map who contributed what across their development history and get the paperwork straight while it is still easy. Describe your situation through our contact form.